Establishing and conducting communications within a network

BACKGROUND OF THE INVENTION

This invention relates generally to methods and systems for establishing and conducting communications between nodes in a network. More particularly, the present invention relates to establishing communications between nodes in a network using predetermined time periods for communications between the nodes and directional pointing of the antenna of each node.

Communications between mobile network nodes have been accomplished using directional antennae, which offer the advantages of higher data rate and longer range than omnidirectional antennae. However, directional antennae alone cannot be used for communications between nodes whose locations are unknown to each other. Therefore, in prior art, directional antennae alone cannot be used to establish communication between nodes, because the location of each node is unknown to the other until both nodes join a common network. Using only directional antennae to establish communications is unreliable because a transmitting network node may not be pointing at a receiving network node when the receiving network node is pointing at the transmitting network node. Thus, an omni-directional antenna is also utilized in prior art to establish temporary, low-rate communications to determine where other nodes reside. After a first node obtains the location of at least one other node that belongs to a network the first node wishes to join, the first node can point its directional antenna towards the other node to establish high-rate, long-range communications. However, using the omni-directional antenna to establish the location of other nodes in the network requires additional spectrum space and power to compensate for the operation of the omni-directional antenna. More specifically, the omni-directional antenna requires additional power for operation as it is not focused in a particular direction. Further, the omnidirectional antenna imposes cost and weight on the node beyond the cost and weight of the directional antennae.

Thus, communicating between network nodes using an omni-directional antenna and a directional antenna is costly because two antennae are required for each network node, one antenna (omni-directional) to establish location and another antenna for directional communication. Additionally, the omni-directional antenna utilizes extra spectrum width as well as additional power to transmit data over long distances.

In view of the foregoing, there is a need for more efficient methods and systems for establishing and conducting communications within a network. Furthermore, there is a need for establishing and conducting communications within a network which utilizes a single antenna for establishing location and conducting communications, wherein the antenna utilizes a more narrow spectrum for communications, and utilizes less power in the transmission and reception of data.

BRIEF DESCRIPTION OF THE INVENTION

Consistent with embodiments of the present invention, systems and methods are disclosed for establishing and conducting communications within a network. In accordance with one embodiment, a method for establishing and conducting communications between a plurality of communication nodes is provided which comprises determining a scheduled time period for communications between a first communication node and a second communication node, determining a direction of transmission for transmitting data from the first communication node to the second communication node, determining a direction of reception for receiving data from the first communication node at the second communication node, and establishing communications between the first communication node and the second communication node.

According to other embodiments, the method for establishing and conducting communications between a plurality of communication nodes may include refinements that improve communications. The refinements may include, but are not limited to, adjustments to communications scheduling, adjustments for altitude between a transmitter and receiver, adjustments compensating for differences in longitude between a transmitter and receiver, adjustments due to the curvature of the earth between the transmitter and receiver, and adjustments due to the beam width of a communications medium.

It is to be understood that both the foregoing brief description and the following detailed description are exemplary and explanatory only, and should not be considered restrictive of the scope of the invention, as described and claimed. Further, features and/or variations may be provided in addition to those set forth herein. For example, embodiments of the invention may be directed to various combinations and sub-combinations of the features described in the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

<figref idrefs="DRAWINGS">FIG. 1</figref> is a diagram illustrating a time phased antenna pointing method for establishing communications within a network.

<figref idrefs="DRAWINGS">FIG. 2</figref> is a diagram illustrating a refinement of the method of <figref idrefs="DRAWINGS">FIG. 1</figref>, compensating for a node that is not at an assumed altitude.

<figref idrefs="DRAWINGS">FIG. 3</figref> is a diagram illustrating a refinement of the method of <figref idrefs="DRAWINGS">FIG. 1</figref>, including a direction offset to compensate for curvature of the earth between two nodes.

<figref idrefs="DRAWINGS">FIG. 4</figref> is a diagram illustrating a refinement of the method of <figref idrefs="DRAWINGS">FIG. 1</figref>, including compensation for an azimuth angle between nodes at different longitudes.

<figref idrefs="DRAWINGS">FIG. 5</figref> is a diagram illustrating a refinement of the method of <figref idrefs="DRAWINGS">FIG. 1</figref>, including compensation for data transmissions where the beam width is not zero.

<figref idrefs="DRAWINGS">FIG. 6</figref> is a diagram illustrating communications between nodes where there is a variable beam width.

<figref idrefs="DRAWINGS">FIG. 7</figref> is an illustration of an antenna pointing pattern.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar parts. While several exemplary embodiments and features of the invention are described herein, modifications, adaptations and other implementations are possible, without departing from the spirit and scope of the invention. For example, substitutions, additions or modifications may be made to the components illustrated in the drawings, and the exemplary methods described herein may be modified by substituting, reordering, or adding stages to the disclosed methods. Accordingly, the following detailed description does not limit the invention. Instead, the proper scope of the invention is defined by the appended claims.

A communications network implementing the methods and systems for establishing and conducting communications between nodes in a network, as described below, provides communications between parties using an antenna to transmit information and another antenna to receive information. In order to ensure the establishment and maintenance of a communications link between parties, each party directs their antenna using an established pattern which is stored in a table in each communications system. Thus, at a designated time in which communications should occur between two parties, the antenna transmitting information will point toward the receiving antenna for a period of time to facilitate communications and the receiving antenna will point toward the transmitting antenna for a corresponding period of time. Once the respective time period expires, each party moves their antenna in another direction which is also stored in the look up table to establish and/or continue communications with another party.

By pointing the antennae in a designated direction at a certain time, an omni-directional antenna is not required because a direction has already been established for which an antenna is expecting to transmit or receive information. Since omni-directional antennae are not required in the communications network, a communications spectrum for communications between nodes in the network can be reduced. In addition, because omni-directional antennas are not required, power required to establish communications between nodes in the network is also reduced, particularly when the parties are separated by large distances.

<figref idrefs="DRAWINGS">FIG. 1</figref> is a diagram illustrating an exemplary method <b>100</b> for establishing communications within a network. The method <b>100</b> facilitates communications between a new node (Node A <b>102</b>) and a node already connected to the network (Node B <b>104</b>) using a directional pointing pattern for phased array antennae as a function of time. The pointing pattern as well as a predetermined schedule for pointing respective antennae and a predetermined communications time length are stored in look-up tables at each of Node A <b>102</b> and Node B <b>104</b>.

The directional pointing pattern, which is subsequently further explained, utilizes a pointing function r(t_i) which uses a unit sphere (4π steradians) and time to determine when and in what direction communications should occur between Node A <b>102</b> and Node B <b>104</b>. The time (t_i) represents a period of time designated for nodes to establish communications. Thus, when Node A <b>102</b> attempts to join the network at (time (t₆)), Node A <b>102</b> points its antenna at a prescribed direction r(t₆) for time t₆in order to establish communications, while Node B <b>104</b> points its antenna at a prescribed direction r(t₆) for time t₆. However, because Node B <b>104</b> is already connected to the network, the function r(t_i) is negated (−r(t₆)) causing Node B <b>104</b> to point its antenna in an anti-parallel, that is, a parallel but opposite direction to that of Node A <b>102</b> establishing a communications link. Specifically, Node A <b>102</b> points toward Node B <b>104</b> and Node B <b>104</b> points toward Node A <b>102</b>.

While the function r(t_i) is useful in establishing communications when a time of flight for messages between Node A <b>102</b> and Node B <b>104</b> is short, and the curvature of the Earth between Node A <b>102</b> and Node B <b>104</b> is minimal, refinements may be required for long range communications. In order to improve the communication range between Node A <b>102</b> and Node B <b>104</b>, a protocol is implemented, in one embodiment, to provide a common time reference between Node A <b>102</b> and Node B <b>104</b>. The time reference is used to ensure that a message transmitted from Node A <b>102</b> arrives at Node B <b>104</b> at a time when the antenna of Node B <b>104</b> is transmitting in an anti-parallel direction to the antenna of Node A <b>102</b>.

Accordingly, method <b>100</b> may be modified for long range communications by assuming a receiving node (Node B <b>104</b>) is at either of two possible altitudes: (1) sea level, if Node A <b>102</b> is transmitting along a vector which intersects the Earth's surface, or (2) a maximum designated altitude for Node B <b>104</b> if Node A <b>102</b> is transmitting along a vector which does not intersect the Earth's surface, for example, 100,000 feet. For example, if Node A <b>102</b> is at sea level and transmits data to a zenith (a point of the celestial sphere that is directly opposite the nadir and vertically above the observer), the assumed altitude of Node B <b>104</b> is, for example, 100,000 feet. Accordingly, if the protocol r(t_i) designates Node A <b>102</b> to point toward the zenith at 300 microseconds after each whole second, then Node B <b>104</b> points toward the nadir at 300 microseconds after each whole second. However, because Node B <b>104</b> is assumed to be at a location 100,000 feet above Node A <b>102</b>, there is a time delay between data transmission and data reception.

Accordingly, in order for Node B <b>104</b> to receive such information at the designated time, i.e. 300 microseconds, Node A <b>102</b> should transmit the data prior to the designated time to ensure the data reaches Node B at the designated time. One example equation for determining when Node A <b>102</b> should transmit the data could be the following: <br /><i>t</i>=(designated transmission time−(altitude of receiver−altitude of transmitter)/speed of light).

Therefore, using the above example numbers, the time equation is the following: <br /><i>t=</i>300 μsec−((100,000 ft−0 ft)/1000 ft/μsec)=200 μsec

Thus, Node A <b>102</b> should transmit information at a time 200 μsec after the beginning of the next whole second in order for the information to be received at Node B <b>104</b> at time 300 μsec after the next whole second in order to accommodate for the distance of 100,000 feet.

However, Node B <b>104</b> may not at be located at the assumed altitude of 100,000 feet. <figref idrefs="DRAWINGS">FIG. 2</figref> illustrates a method of further refining method <b>100</b> to compensate for a node which is not located at an assumed altitude (Node <b>202</b>). While the time for transmission by Node A <b>102</b> if Node B <b>104</b> is at an altitude of 100,000 feet is at 200 μsec after the next whole second, Node B <b>104</b> may be adjusted to receive information at the designated time even though Node B <b>104</b> is at an altitude of 50,000 feet instead of 100,000 feet. By assuming that node B is at a maximum altitude, h_max, a nominal range to Node B <b>104</b> may be computed using the function, r(t)=f(α, h_a, h_max), with ha being an actual altitude of node B <b>104</b> and α being an angle from node A <b>102</b> to node B <b>104</b>. Thus, an equation for adjusting the timing based on a difference of altitude could be the following: <br /><i>t</i>=300 μsec−((100,000 ft−50,000 ft)/1000 ft/μsec)=250 μsec

Thus, Node B <b>104</b> adjusts its timing for receiving data to 250 μsec after the next whole second instead of time 300 μsec after the next whole second to compensate for the difference in distance by 50,000 feet.

In addition to calculating transmission time offsets for transmission and reception of data between Node A <b>102</b> and Node B <b>104</b>, <figref idrefs="DRAWINGS">FIG. 3</figref> illustrates a method of further refining method <b>100</b> to include a direction offset to compensate for the curvature of the Earth between Node A <b>102</b> and Node B <b>104</b>. The direction offset may be larger when Node A <b>102</b> and Node B <b>104</b> are separated by a large distance, for example, 500 kilometers.

Thus, when Node A <b>102</b> transmits data along a direction r(t_i) at designated time t_iand at an elevation angle (α), where α is elevation as a function of (r(t))−Δα to compensate for the curvature of the Earth during transmission. Node B <b>104</b> could alter its angle of reception to compensate for the curvature of the Earth. In one embodiment, such compensation employs adjusting the reception angle at Node B <b>104</b> to the elevation angle α, where α is higher in elevation than −r(t_i)+(Δα_max−Δα_B) to ensure Node B <b>104</b> remains at −r(t_i), i.e., anti-parallel to that of node A <b>102</b>.

<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates a method of further refining method <b>100</b> to compensate for an azimuth angle (horizontal direction expressed as the angular distance between the direction of a fixed point (such as the north pole) and the direction of the object) when Node A <b>102</b> and Node B <b>104</b> are located at different longitudes. For example, if Node A <b>102</b> is located at 90 degrees west longitude and ten miles from the North pole and Node B <b>104</b> is at the assumed altitude of 100,000 feet and located at 0 longitude and ten miles from the North pole, at time t_i, Node B <b>104</b> computes an angle of reception −r(t_i) to be northwest, i.e. an azimuth of 315 degrees. Node A <b>102</b> computes a transmission angle r(t_i) to be northeast, i.e. an azimuth of 45 degrees; however, due to being located at different longitudes, when Node A <b>102</b> transmits data at an azimuth of 45 degrees, Node B <b>104</b> will receive the data accordingly at an azimuth angle of 315 degrees due to the 90 degree difference in longitude.

Accordingly, during a transmission for an instance in which Node A <b>102</b> and Node B <b>104</b> are located at different longitudes, Node A <b>102</b> transmits data assuming that Node B is at the designated altitude of 100,000 feet and an azimuth angle az(t_i), where az(t_i)=f(−az_hmax(t_i), h_A, h_max). However, if Node B <b>104</b> is not located at the designated altitude, Node B <b>104</b> adjusts the angle of reception to −az_B(t_i). Node B <b>104</b> projects from its location along R(t) to the designated altitude, then computes the change in longitude along that path. The changes in longitude become the angle adjustment.

While the above illustrated method and refinements provide for communications between Node A <b>102</b> and Node B <b>104</b> using a communications medium having an ideal beam width of zero, communications using antennae having beam widths which are not equal to zero may require additional adjustments to facilitate communications between Node A <b>102</b> and Node B <b>104</b>. <figref idrefs="DRAWINGS">FIG. 5</figref> illustrates a method of further refining method <b>100</b> to compensate for data transmissions using a communications medium having a beam width which does not equal zero.

In a transmission in which the transmission beam width does not equal zero, a degree of uncertainty is introduced because the transmission signal travels in the form of a cone instead of along a line, similar to a laser beam. Thus, the transmission signal forms an ellipse at a point of intersection between the transmission beam and the altitude plane of Node B <b>104</b>. Accordingly, adjustments made by Node B <b>104</b> to receive the transmission signal may not allow for the reception of data from Node A <b>102</b> correctly because Node B <b>104</b> cannot precisely calculate the distance between itself and Node A <b>102</b> (range uncertainty). For example, Node B may reside at location <b>104</b> instead of <b>502</b>. Range uncertainty may be equated to the term, Δr=range_α*f(α, ΔΘ, h_B).

Factors contributing to range uncertainty include transmission beam width, elevation angle for the transmission beam, and the difference in altitude between Node A <b>102</b> and Node B <b>104</b>. Range uncertainty is related to the temporal dispersion of data being transmitted because as the communication beam width increases or the elevation angle for the transmission beam is small, i.e., transmissions near the horizon, range uncertainty and temporal dispersion increases. Temporal uncertainty may be equated to the term Δt=Δr/c.

Thus, an adjustment can be employed at Node A <b>102</b> to minimize timing errors which could occur due to the imprecision in calculating the location of Node B <b>104</b>. In addition, because angular errors due to the imprecision of locating Node B <b>104</b> are normally less than the beam width used for transmissions, these errors may be deemed insignificant when correcting for a non-zero beam width. The angular error may be as large as half the beam width. If the angular error is larger, then Node B <b>104</b> is within the beam of a different pointing direction, r(t_j). The adjustment at Node A <b>102</b> may include transmitting multiple messages within a short duration, for example, several messages having a duration of 1.2 microseconds may be transmitted to Node B <b>104</b> during a designated communication period, for example, 150 microseconds. Another adjustment includes transmitting a message at the beginning of a designated and at the end of the designated time period. Yet another adjustment includes utilizing a minimum spread of repeated messages in the direction r(t_i) to ensure that Node B <b>104</b> receives at least one message during the time period t_i.

While Node A <b>102</b> normally uses an antenna having a fixed beam width, Node A <b>102</b> could also use an antenna which has a variable beam width as illustrated in <figref idrefs="DRAWINGS">FIG. 6</figref>. By using a transmitter and antenna that provide a variable beam width, Node A <b>102</b> could transmit data to Node B <b>104</b> using a wide beam width when such transmissions are near-vertical. In near vertical cases, the range from Node A <b>102</b> to node B <b>104</b> is less than the maximum node altitude, so a narrow beam is not necessary to achieve adequate gain. More specifically, range uncertainty when using wide beams for transmissions during near-vertical communications between Node A <b>102</b> and Node B <b>104</b> is not significant due to the high angle of elevation. As further described with respect to <figref idrefs="DRAWINGS">FIG. 7</figref>, a large fraction of a unit sphere near a zenith can be covered with a wider beam with one or a couple of messages. As the beam is transmitted in a substantially vertical direction, it is not likely to be intercepted, for example, by an enemy or other unintended recipient.

<figref idrefs="DRAWINGS">FIG. 7</figref> illustrates a method of determining where antennae should point at a given time period (pointing pattern). Such information is, in one example embodiment, stored in the look-up table at each node. When a node, for example, Node A <b>102</b> desires to establish communications with another node in a network, i.e., join the network, the antenna at Node A <b>102</b> may access the pointing pattern from the look-up table to determine which direction to point the antenna during a given time period.

The pointing pattern may be based on a unit sphere and may follow a honeycomb pattern. A direction for the first pointing direction may point towards the nadir, i.e. direction (0,1), subsequently moving outward in a sphere forming a ring around the nadir. The movement may be repeated while the direction moves further away from the nadir. However, when using the curved surface of the unit sphere, the diameter of circular beams may be reduced as the pointing pattern moves further away from the nadir to remain within the surface of the unit sphere.

The pointing pattern is determined, in one embodiment, using the following table and formulas:

<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="21pt" align="center" /><colspec colname="2" colwidth="28pt" align="center" /><colspec colname="3" colwidth="28pt" align="center" /><colspec colname="4" colwidth="56pt" align="center" /><colspec colname="5" colwidth="28pt" align="center" /><colspec colname="6" colwidth="42pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="6" align="center" rowsep="1" /></row><row><entry /><entry /><entry /><entry>R</entry><entry /><entry>Outer R</entry><entry>Outer R</entry></row><row><entry /><entry>Ring</entry><entry>N</entry><entry>(rads)</entry><entry>Residue</entry><entry>(rads)</entry><entry>(deg)</entry></row><row><entry /><entry namest="offset" nameend="6" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="21pt" align="char" char="." /><colspec colname="2" colwidth="28pt" align="char" char="." /><colspec colname="3" colwidth="28pt" align="char" char="." /><colspec colname="4" colwidth="56pt" align="center" /><colspec colname="5" colwidth="28pt" align="char" char="." /><colspec colname="6" colwidth="42pt" align="char" char="." /><tbody valign="top"><row><entry /><entry>0</entry><entry>1</entry><entry>0.1020</entry><entry>0</entry><entry>0.102</entry><entry>5.84</entry></row><row><entry /><entry>1</entry><entry>6</entry><entry>0.1104</entry><entry>−6.15E−09</entry><entry>0.323</entry><entry>18.49</entry></row><row><entry /><entry>2</entry><entry>12</entry><entry>0.1097</entry><entry>−4.02E−08</entry><entry>0.542</entry><entry>31.07</entry></row><row><entry /><entry>3</entry><entry>18</entry><entry>0.1053</entry><entry>  −9E−08</entry><entry>0.753</entry><entry>43.13</entry></row><row><entry /><entry>4</entry><entry>24</entry><entry>0.0984</entry><entry>−1.16E−07</entry><entry>0.950</entry><entry>54.41</entry></row><row><entry /><entry>5</entry><entry>30</entry><entry>0.0903</entry><entry>−1.02E−07</entry><entry>1.130</entry><entry>64.76</entry></row><row><entry /><entry>6</entry><entry>36</entry><entry>0.0817</entry><entry>−6.24E−08</entry><entry>1.294</entry><entry>74.12</entry></row><row><entry /><entry>7</entry><entry>42</entry><entry>0.0733</entry><entry> −2.5E−08</entry><entry>1.440</entry><entry>82.52</entry></row><row><entry /><entry>8</entry><entry>48</entry><entry>0.0653</entry><entry>−4.82E−09</entry><entry>1.571</entry><entry>90.00</entry></row><row><entry /><entry namest="offset" nameend="6" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

The formula in “Ring” is the prior row's value+the formula in “N”, or (Ring×6). “N” is the number of beams in this ring, and “R” is the angular radius of beams in the ring. “Residue” is calculated as (2×N)×R−(2π×sin((“Outer R of prior row”+R)/1)), “Outer R (rads)” is calculated as “Outer R of prior row”+2×R, and “Outer R (deg)” is calculated as “Outer R (rads)”×180/π. R, in one embodiment, is optimized using an Excel solver.

Accordingly, the approach used in devising this pattern may be as follows: After ring 0, each succeeding ring has a number of beams equal to six times the index of the ring. A communications systems manufacturer may select the number of rings to use thereby allowing system software to iterate the sizes of beams in each ring in order to get a total angle of 90 degrees (pole to equator) across all the rings. The constraints for the solver may be that all values in the “Residue” column are zero (within a specified precision.)

An exemplary table of the pointing pattern of <figref idrefs="DRAWINGS">FIG. 7</figref> for storage in the look-up table could be the following:

<tables id="TABLE-US-00002" num="00002"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="49pt" align="center" /><colspec colname="2" colwidth="14pt" align="center" /><colspec colname="3" colwidth="56pt" align="center" /><colspec colname="4" colwidth="28pt" align="center" /><colspec colname="5" colwidth="70pt" align="center" /><thead><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row><row><entry /><entry /><entry>R</entry><entry>Outer R</entry><entry>Outer R</entry></row><row><entry>Ring</entry><entry>N</entry><entry>(rads)</entry><entry>(rads)</entry><entry>(deg)</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="49pt" align="center" /><colspec colname="2" colwidth="14pt" align="char" char="." /><colspec colname="3" colwidth="56pt" align="char" char="." /><colspec colname="4" colwidth="28pt" align="char" char="." /><colspec colname="5" colwidth="70pt" align="char" char="." /><tbody valign="top"><row><entry>0</entry><entry>1</entry><entry>0.1020</entry><entry>0.102</entry><entry>5.84</entry></row><row><entry>1</entry><entry>6</entry><entry>0.1104</entry><entry>0.323</entry><entry>18.49</entry></row><row><entry>2</entry><entry>12</entry><entry>0.1097</entry><entry>0.542</entry><entry>31.07</entry></row><row><entry>3</entry><entry>18</entry><entry>0.1053</entry><entry>0.753</entry><entry>43.13</entry></row><row><entry>4</entry><entry>24</entry><entry>0.0984</entry><entry>0.950</entry><entry>54.41</entry></row><row><entry>5</entry><entry>30</entry><entry>0.0903</entry><entry>1.130</entry><entry>64.76</entry></row><row><entry>6</entry><entry>36</entry><entry>0.0817</entry><entry>1.294</entry><entry>74.12</entry></row><row><entry>7</entry><entry>42</entry><entry>0.0733</entry><entry>1.440</entry><entry>82.52</entry></row><row><entry>8</entry><entry>48</entry><entry>0.0653</entry><entry>1.571</entry><entry>90.00</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

Accordingly, the pointing pattern could sweep out in a pattern going from equator to zenith. Another pointing pattern could employ a pattern going from the equator to zenith and from the equator to the nadir at the same time. Each of the two beams could receive data in opposite directions during each time slot Such a pattern could cover the unit sphere in half the time, leaving more time for network activity unrelated to establishing communications with the network. The starting point for the pointing pattern above is arbitrary and may utilize another starting point or sequence of pointing.

A system for implementing the methods and refinements described above may include an electronically steerable antenna for communications, an altimeter to determine altitude, an attitude measuring device to determine orientation, a time measuring device, for example, an atomic clock, and a computing device and database for determining a pointing direction for a prescribed time period which may be stored in the look-up table.

Thus, the systems and methods for establishing and conducting communications within a network allow for communications to be established by nodes joining a network using the same antenna used during normal communications thereby reducing spectrum and power requirements, as well as the cost of additional equipment (omni-directional antenna). Antennae which can be employed may include a phased array antenna or some other type of steerable antenna. Other devices to determine altitude which may be utilized include a global positioning device (GPS) or radar altimeter. In addition, communications may be established using the above systems and methods between non-terrestrial nodes, i.e., two or more satellites. The use of the terms receiver or transmitter are not meant to be exhaustive and may include other communication devices such as transceivers and optical communication devices.

The systems and methods described above may be used in a variety of applications, for example, military communication applications. Such an application is beneficial because the systems and methods described above reduce the possibility of signal detection and signal interception because each antenna points toward a specific location for a predetermined period of time using a narrow, directional beam. Thus, the locations or plans of friendly forces are harder to be compromised by the enemy.

The invention may be practiced in an electrical circuit comprising discrete electronic elements, packaged or integrated electronic chips containing logic gates, a circuit utilizing a microprocessor, or on a single chip containing electronic elements or microprocessors. The invention may also be practiced using other technologies capable of performing logical operations such as, for example, AND, OR, and NOT, including but not limited to mechanical, optical, fluidic, and quantum technologies. In addition, the invention may be practiced within a general purpose computer or in any other circuits or systems.

The present invention may be embodied as systems, methods, and/or computer program products. Accordingly, the present invention may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, embodiments of the present invention may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. A computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

The computer-usable or computer-readable medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). Note that the computer-usable or computer-readable medium could even be paper or another suitable medium, upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.

Embodiments of the present invention are described above with reference to block diagrams and/or operational illustrations of methods, systems, and computer program products according to embodiments of the invention. It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved.

While certain features and embodiments of the invention have been described, other embodiments of the invention may exist. Furthermore, although embodiments of the present invention have been described as being associated with data stored in memory and other storage mediums, aspects can also be stored on or read from other types of computer-readable media, such as secondary storage devices, like hard disks, floppy disks, or a CD-ROM, a carrier wave from the Internet, or other forms of RAM or ROM. Further, the steps of the disclosed methods may be modified in any manner, including by reordering stages and/or inserting or deleting stages, without departing from the principles of the invention.

While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.